Q17 - an audiophile approach to perfect sound

My latest audiophile approach named Q17.
So far the best sounding amplifier I ever made. Harmonic reach with exceptional bass response and 3d soundstage.
Archive contain everything. Full amplifier description and operation. Ltspice asc file for simulation. KiCad source for Q17 and his power supply. Gerbers zipped, so you may pick and drop on your favourite PCB manufacture. BOM with current active parts for Q17 and power supply.
Detailed description on how I made the PCB inductor and more, is also incuded in zip.
Inside zip:
LTSpice - contain asc file
ps - power supply KiCad source files
Q17 - amplifier KiCad source files
Spiki - inductor generator - python script to generate inductors in KiCad
Q17project_presentation.pdf - detailed presentation - bill of materials included
Q17 is on GitHub under GPL3 - Q17 is an open-source hardware project
Q17 is on hackaday.io
ngspice simulation
How to order your transformer
How to order your own PCB from JLCPCB, or click & order your Q17 with dual output pair PCB @ PCB from PCBWay
You have extra money and wanna buy directly from me, subscribe to this GB list.
Purchase parts for one channel with one click from mouser.
Purchase parts for active power supply from mouser. Does not include synchronous rectifiers and optional decoupling MKP.

Enjoy !

Edit 23.July.2021 If you build this amplifier, please give him a serious burn-in. All these mosfet's will start to sing after 200-300 hours.
You may download latest KiCad for your OS from >>> KiCad Downloads

Edit 25.July.2021 GerberQ17.zip is for amplifier pcb and gerberPS.zip for power supply.
Upload each zip file separately to jlcpcb. Jlcpcb will process one file at a time as separate orders.

Edit 26.July.2021 There is an error on output connector on GerberQ17.zip. Don't use this file until I correct this.

Edit 27.July.2021 Output connector issue is cleared. See this post for latest archive > Q17 - a QUAD405 audiophile approach to perfect sound

Edit 12.Aug.2021 Mounting holes have been added to power supply pcb. Gerbers available here >> Q17 - a QUAD405 audiophile approach to perfect sound

Q17c.jpeg Q17.jpeg Q17-2.jpeg E4UPJ3JXEAUE0fX.jpg aps.jpeg


  • Q17.zip
    3.4 MB · Views: 889
Last edited:
Joined 2002
Nice! Still I would use a bipolar capacitor for C2, a DC blocking coupling cap and RC input filter at the input certainly with OPA1641.

Coincidentally I have a defective and mistreated 405 with 1 blown channel in front of me but do these boards fit in an original Quad 405?!
Last edited:
  • Like
Reactions: 1 user
Yes, a bipolar for C2 is the best choice and I mentioned this in my dissertation.
Q17 board will not fit original 405 boards, but design is open. Fell free to design your own.
Embedded coil will take some space and to preserve original 405 PCB layout this must be made with smd parts.
THT is more diy friendly, hence my choice.

Last edited by a moderator:
@piersma I made measurements, but I did not record them as I care much more on how the amplifier sound. As soon I made a modification, my first thing to do is to listen and not measure. IMD/THD have only been simulated and you may use ltspice file to make you an idea. The single measurement for which I fire my scope is square at 10KHz or higher. As soon I have time I'll measure again and post here.

@chat72 The PCB in the first post was for prototype, therefore several issues have been corrected and since then it was 2 times partially redesigned. Even so, there is room for improvement, especially on component description.

Last edited by a moderator:
Hello Tibi,

I am very impressed with your work. Thank you very much for your documentation.
I can't open the Kicad files yet, as I couldn't find the download for the trial version 6.0.0.r as well as for 5.99.

I have one more question about it - I must note, I don't really know anything about MosFET as an amplifier, and my experiment with it sounded - as you describe it in the documentation also of such constructs - asleep.

You write about MosFET with 120 Siemens as final transistors. Do I understand correctly that the change to these types do not require a change in the layout, but is there so that even speakers - such as Wilson Audio with an impedance around 2Ohm - can be pushed with it?
My speaker constructs usually have an impedance minimum around 3.4 ohms and a maximum around 15 ohms in the midrange. Are the MosFET FQA46N15 FQA36P/15 suitable for this, or rather not more?

Regards Tim
Hello Tim,

You may download kicad 5.99 for macbook from >>> https://kicad-downloads.s3.cern.ch/osx/nightly/kicad-unified-20210722-154659-8d1dd1f8b0.dmg
for windows from >>>https://kicad-downloads.s3.cern.ch/windows/nightly/kicad-msvc.r23356.1a301d8eea-x86_64.exe

IXFK220N20X3 and IXTK120P20T are drop in replacement for FQA46N15 & FQA36P15 and stage A have enough juice to drive them both.
However, I personally fall in love with FQA46N15 & FQA36P15, these are very musical and involving. In the same time, FQA46N15 & FQA36P15, are able to drive very low impedances well below 2ohm. Your Wilson's will feel the power. :)
But when we talk about power, there is always need for more. Just to praise myself, a 8 pair design is under construction, but I'll not make it public because is extremist in all ways. :bigeyes:

Thanks & Regards,
Hello Tibi,

Thank you for the link, I didn't find it with Google.

Fortunately I don't have Audio Wilson speakers :D, I just wanted to understand a bit more how you select the MosFET.

I can fully understand you not publishing your own amp. If it gets really eccentric, you should keep it to yourself, otherwise it just gives endless discussions without others really trying it out.
Nevertheless, I find your concept of the Q17 very interesting and will probably pre-order the parts. There are supposed to be semiconductors again in 2022. ;)

Would you sell PCBs? Well, I'm not thrilled that you soldered on the OPA, but those are details.

One more thing, have you already tried the OPA1611? TI offers it as a reference for single OP.

Regards Tim
FQA46N15 & FQA36P15 make a very good pair.
I do not sell PCB's. You may drop the gerber zip file on jlcpcb and get 5 boards for under 10$ including shipping to EU.
On other side, I know that someone in Romania started to redesign the PCB and will conduct a GB. If here is any interest in this this project, I'll ask him to post here as well.

I have OPA1611 in one of my dac's and is sounding very good.
If you like it, use it.

Inside Q17.zip, under Q17 directory, are another two zip files. One GerberQ17.zip for amplifier pcb and one gerberPS.zip for power supply.
Upload each zip file separately to jlcpcb. Jlcpcb will process one file at a time.

5 standard boards - 7.7$
audiophile boards with 2oz, enig, black finish - 92.68$ :D



  • Capture.PNG
    222.2 KB · Views: 1,571
  • Capture1.PNG
    184.1 KB · Views: 1,537
Last edited by a moderator: